Components that use vehicle battery power and generated voltage from a running vehicle engine comprise a large portion of the aftermarket vehicle accessories market. Power from generators in running vehicles is used for charging cellular telephones, and for powering compact disc players, flexible lighting assemblies, and a host of other products. One of the most popular connecting point for many accessories that are not permanently installed is the cigarette lighter bay on the vehicle dashboard. Newer vehicles now come with other power outlets similar to grounded 2 and 3-prong outlets common in the home. It is believed that vehicles in the future will be provided with DC power outlets of perhaps, up to 40 volts DC.
In order to successfully operate some types of accessories that may be permanently installed in a vehicle, such as a compact disc player or an electronic navigation system for example, considerable wiring, typically to the electronic ignition harness, must be undertaken to ensure the proper voltage and ground. Products that can be connected and powered on through the lighter bay or other vehicle DC power socket are comparatively simple in design and function. Some products use the engine status of running or not running as input to their stated functions. If a cell phone, for example, were to be charged when the vehicle is not running, the power drawn to the phone comes directly from the battery of the vehicle. Therefore it is needed to include some form of vehicle engine status intelligence into the design of third-party systems and applications.
Some applications use physical vibration sensors to determine when a vehicle is running or not. A difficulty with these sensors is that they are prone to failure because of a delicate mechanical design. Also, inadvertent vibration can set off an engine status sensor and cause a related application to miss fire. Likewise, many third-party applications contain their own connection circuitry logic for interfacing with the automobile ignition wiring. Such applications are not easily connected or disconnected, and the connection circuitry is not easily detachable once installed. It would be very inconvenient, if not impossible, for end users of an engine-powered product to connect an engine status signal for their newly acquired third party apparatus to the engine's ignition control circuitry without knowledge of engine ignition electronics as a prerequisite, as well as familiarity with the specific wiring of the product in question.
What is clearly needed in the art is an engine-status detection circuitry that can be used to monitor status of a vehicle engine, and to connect a variety of both self-powered and engine-powered third-party applications to a convenient point of entry into a vehicle's circuitry. Such circuitry could be provided inexpensively and would much simplify installation and use of aftermarket accessories with vehicle electrical systems.